This disclosure relates to social networks and, more particularly, to determining sub-social networks based on contextual inferencing. A social networking system refers to a computing platform that allows users to build social networks, e.g., social relations, among people who share similar interests, activities, backgrounds or real-life connections. Users may communicate with one another through the social networking system. In the typical case, a user joins a social networking system and begins to establish associations with other users. The group of users on the social networking system with whom a selected user has actively accepted within the group may be referred to as the “social network” of the selected user.